Chapter 8

Calculate \(\mathrm{pH}\) at which an acid indicator HIn with concentration \(0.1 \mathrm{M}\) changes its colour \(\left(\mathrm{K}_{\mathrm{a}}\right.\) for \(\mathrm{HIn}=\) \(\left.1 \times 10^{-5}\right)\)

What is the \(\mathrm{pH}\) of a mixture obtained by mixing \(75 \mathrm{ml}\) \(\mathrm{M} / 5 \mathrm{HCl}\) and \(25 \mathrm{ml} \mathrm{M} / 5 \mathrm{NaOH}\) aqueous solution?

The dissociation constant of a substituted benzoic acid is \(1.0 \times 10^{-4}\) at \(25^{\circ} \mathrm{C}\). The \(\mathrm{pH}\) of \(0.01 \mathrm{~m}\) solution of its sodium salt is

Solubility of \(\mathrm{Ca}(\mathrm{OH})_{2}\) is \(\mathrm{S}\) mol litre \(^{-1} .\) The solubility product (Ksp) under the same condition is (a) \(4 \mathrm{~S}^{3}\) (b) \(3 \mathrm{~S}^{4}\) (c) \(4 \mathrm{~S}^{2}\) (d) \(\mathrm{S}^{3}\)

One of the following species acts as both Bronsted acid and base (a) \(\mathrm{H}_{2} \mathrm{PO}_{2}\) (b) \(\mathrm{HPO}_{3}^{2}\) (c) \(\mathrm{HPO}_{4}^{2}\) (d) all of the above

An aqueous solution of \(\mathrm{lM} \mathrm{NaCl}\) and \(\mathrm{IM} \mathrm{HCl}\) is a) not a buffer but \(\mathrm{pH}<7\) (b) not a buffer but \(\mathrm{pH}>7\) (c) a buffer with \(\mathrm{pH}<7\) (d) a buffer with \(\mathrm{pH}>7\)

pH of \(0.005 \mathrm{M}\) calcium acetate (pKa of \(\mathrm{CH}_{3} \mathrm{COOH}\) \(=4.74\) ) is \(\quad\) [2002] (a) \(7.37\) (b) \(9.37\) (c) \(9.26\) (d) \(8.37\)

The solubility in water of a sparingly soluble salt \(\mathrm{AB}_{2}\) is \(1.0 \times 10^{-5} \mathrm{molL}^{-1}\). Its solubility product number will be (a) \(4 \times 10^{-15}\) (b) \(4 \times 10^{-10}\) (c) \(1 \times 10^{-15}\) (d) \(1 \times 10^{-10}\)

Which of the following is not true? [2003] (a) The conjugate base of \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)is \(\mathrm{HPO}_{4}^{2-}\) (b) \(\mathrm{pH}+\mathrm{pOH}=14\) for all aqueous solutions (c) the \(\mathrm{pH}\) of \(1 \times 10^{-8} \mathrm{M} \mathrm{HCl}\) is 8 . (d) 96500 coulombs of electricity when passed through a \(\mathrm{CuSO}_{4}\) solution deposit 1 gram equivalent of copper at the cathode

When rain is accompanied by a thunderstorm, the collected rain water will have a \(\mathrm{pH}\) value (a) slightly lower than that of rain water without thunderstorm (b) slightly higher than that when the thunderstorm in not there (c) uninfluenced by occurrence of thunderstorm (d) which depends on the amount of dust in air

The conjugate base of \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)is (a) \(\mathrm{HPO}_{4}^{2-}\) (b) \(\mathrm{H}_{3} \mathrm{PO}_{4}\) (c) \(\mathrm{PO}_{4}^{3-}\) (d) \(\mathrm{P}_{2} \mathrm{O}_{5}\)

The molar solubility (in \(\mathrm{mol} \mathrm{L}^{-1}\) ) of a sparingly soluble salt \(\mathrm{MX}_{4}\) is ' \(\mathrm{s}^{\prime}\). The corresponding solubility product is Ksp.s is given in terms of Ksp by the relation [2004] (a) \(\mathrm{s}=(\mathrm{Ksp} / 256)^{1 / 5}\) (b) \(\mathrm{s}=(128 \mathrm{Ksp})^{1 / 4}\) (c) \(\mathrm{s}=(\mathrm{Ksp} / 128)^{1 / 4}\) (d) \(\mathrm{s}=(256 \mathrm{Ksp})^{1 / 5}\)

Hydrogen ion concentration in \(\mathrm{mol} / \mathrm{L}\) in solution of \(\mathrm{pH}\) 5.4 will be (a) \(3.88 \times 10^{6}\) (b) \(3.98 \times 10^{-6}\) (c) \(3.98 \times 10^{3}\) (d) \(3.68 \times 10^{-6}\)

The conjugate base of \(\mathrm{OH}^{-}\)is (a) \(\mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{O}^{2}\) (c) \(\mathrm{O}^{-}\) (d) \(\mathrm{O}_{2}\)

The solubility product of a salt having general formula \(\mathrm{MX}_{2}\) in water is, \(4 \times 10^{-12}\) \([2005]\) The concentration of \(\mathrm{M}^{2+}\) ions in the aqueous solution of the salt is (a) \(1.6 \times 10^{-4} \mathrm{M}\) (b) \(2.0 \times 10^{-6} \mathrm{M}\) (c) \(1.0 \times 10^{-4} \mathrm{M}\) (c) \(4.0 \times 10^{-10} \mathrm{M}\)

Four species are listed below \([\mathbf{2 0 0 8}]\) (I) \(\mathrm{HCO}_{3}^{-}\) (II) \(\mathrm{H}_{3} \mathrm{O}^{+}\) (III) \(\mathrm{HSO}_{4}^{-}\) (IV) \(\mathrm{HSO}_{3} \mathrm{~F}\) Which one of the following is the correct sequence of their acid strength? (a) IV \(<\mathrm{II}<\mathrm{III}<\mathrm{I}\) (b) \(\mathrm{II}<\mathrm{III}<\mathrm{I}<\mathrm{IV}\) (c) \(\mathrm{I}<\mathrm{III}<\mathrm{II}<\mathrm{IV}\) (d) III \(<\mathrm{I}<\mathrm{IV}<\mathrm{II}\)

The pKa of a weak acid, HA is \(4.80\). The \(\mathrm{pK}_{\mathrm{b}}\) of a weak base, \(\mathrm{BOH}\) is \(4.78\). The \(\mathrm{pH}\) of an aqueous solution of the corresponding salt, BA will be \([2008]\) (a) \(9.58\) (b) \(4.79\) (c) \(7.01\) (d) \(9.22\)

Solid \(\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\) is gradually dissolved in a \(1.0 \times 10^{-4}\) \(\mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}\) solution. At what concentration of \(\mathrm{Ba}^{2+}\) will precipitate being to form? \(\left(\mathrm{K}_{s p}\right.\) for \(\left.\mathrm{Ba} \mathrm{CO}_{3}=5.1 \times 10^{-9}\right):\) (a) \(5.1 \times 10^{-5} \mathrm{M}\) (b) \(8.1 \times 10^{-8} \mathrm{M}\) (c) \(8.1 \times 10^{-7} \mathrm{M}\) (d) \(4.1 \times 10^{-5} \mathrm{M}\)

Solubility product of silver bromide is \(5.0 \times 10^{-13} .\) The quantity of potassium bromide (molar mass taken as \(120 \mathrm{~g} \mathrm{~mol}^{-1}\) ) to be added to 1 litre of \(0.05 \mathrm{M}\) solution nitrate to start the precipitation of \(\mathrm{AgBr}\) is [2010] (a) \(1.2 \times 10^{-10} \mathrm{~g}\) (b) \(1.2 \times 10^{-9} \mathrm{~g}\) (c) \(6.2 \times 10^{-5} \mathrm{~g}\) (d) \(5.0 \times 10^{-8} \mathrm{~g}\)

At \(25^{\circ} \mathrm{C}\), the solubility product of \(\mathrm{Mg}(\mathrm{OH})_{2}\) is \(1.0 \times 10^{-11} .\) At which \(\mathrm{pH}\), will \(\mathrm{Mg}^{2+}\) ions start precipitating in the form of \(\mathrm{Mg}(\mathrm{OH})_{2}\) from a solution of \(0.001\) M \(\mathrm{Mg}^{2+}\) ions? \([2010]\) (a) 9 (b) 10 (c) 11 (d) 8

How many litres of water must be added to litre of an aqueous solution of \(\mathrm{HCl}\) with a \(\mathrm{pH}\) of 1 to create an aqueous solution with \(\mathrm{pH}\) of \(2 ?\) (a) \(2.0 \mathrm{~L}\) (b) \(9.0 \mathrm{~L}\) (c) \(0.1 \mathrm{~L}\) (d) \(0.9 \mathrm{~L}\)